1. Field of the Invention
This invention relates to a process for producing room temperature curable organopolysiloxane compositions suitable for use as sealing agents and coating agents.
2. Prior Art
RTV silicone rubber compositions of the condensation reaction type are well known in the art which cure into silicone rubber at room temperature in the presence of moisture in air. They are widely used as sealing agents, adhesives and potting agents in a variety of industrial fields including mechanical, electrical and building fields.
In silicone rubber compositions, finely divided silica is often used as a reinforcing filler. High loading of silica is necessary in order to achieve a high strength or tear strength. High loading of silica, however, imparts thixotropy to RTV silicone rubber compositions. When such thixotropic compositions are applied, the coatings in uncured state lack sags and runaway and hence, self-leveling. In order that such coatings be self-leveling, it is a common practice to heat treat a mixture of the base polymer and the filler at 150 to 180.degree. C. for about 1 to 2 hours. However, the heat treatment is disadvantageous from the time and cost standpoints.
Therefore, an object of the invention is to provide a method for preparing a room temperature curable organopoly-siloxane composition which method is successful in improving the flow and self-leveling of the composition without a need for heat treatment, so that the composition is suitable as sealing agents and coating agents.